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Thread: Old ATF or Treasury video of MG conversions link

  1. #1
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    Old ATF or Treasury video of MG conversions link

    Someone a while ago posted a link to an old ATF or Treasury Dept Video about full autos. They were shooting it into a bullet trap in the floor (?)
    In one part they fire a converted M1 Garand that got away.

    Anyone have a link to that video?
    I tried a google/Youtube search, but no luck

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    Are you sure it wasn't the RPB video RPB used in the lawsuit against the ATF re. the open bolt semi MACS?

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    Quote Originally Posted by timgunfreak View Post
    Are you sure it wasn't the RPB video RPB used in the lawsuit against the ATF re. the open bolt semi MACS?
    This?

    https://youtu.be/90o4ENzfrjA

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    O Mr. Peabody your a very naughty naughty little man... the anti fun police all licking their 1982 chops still ha ha!

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    That's the video THANKS!!

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    Registered User timgunfreak's Avatar
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    Who else thinks RPB Industries would have been a fun place to work at prior to July 1982?

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    Love their test fire setup, looks like a hatch over the dirt under the building!

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    I wouldn't want to use that video in a modern courtroom; judge would try to say that since semi's are so easy to convert, they should be banned

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    Gimme another mag! LOL

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    Those folks knew how to have a good time.

    Imagine any animals that were unfortunate enough to have picked that crawlspace as a home.

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    I am somewhat curious as to how they got the AR-7 to run in full auto so well. From what I've read, there are only a handful of transferable, full auto AR-7s, mostly due to the lack of a good way to overcome bolt bounce and the attendant stoppages after a couple rounds. Converting an AR-7 to fire full auto was very easy to do. The first AR-7s had to be modified to avoid "stringing" of several rounds; as did the initial version of the Intratec Scorpion .22LR pistol, which used a fire control group based off the AR-7 design. Yet in the video, their AR-7 appears to be able to do mag dumps without fail.

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    All they were doing was silver soldering a piece of music wire to the bottom of the bolt breechface. Laid flat vertically it essentially becomes a firing pin, crushing the rim as the bolt closes. On the bottom, the wire pushes the cartridge out of the mag and into the chamber so no issues with the rising rim hitting an extended firing pin during feeding. However, the stock hammer fire setup was retained. When he loaded the first round he rode the bolt home, letting it close gently enough it did not set off the first round with the wire. After he pulled the trigger, firing the first round with the OEM setup hammer hits firing pin method, the bolt would cycle and now hitting the round full force when the bolt closes the wire essentially converting it to an open bolt fixed firing pin system. With no means of stopping it except running out of ammo or jamming. He apparently had one of the good AR7 and mag combos that was reliable feeding. That appears to have been what they did with all the .22s they converted, first shot by the oem method, then empty the mag as the bolt cycled full force.

    Bolt bounce is not an issue normally with an open bolt fixed firing pin system as if it does bounce back it is after the round has already fired. With a hammer or striker system that drops the hammer or firing pin as the bolt closes can have problems with bolt bounce as it may close and then the firing pin is too far away from the cartridge as the bolt is bouncing back and the firing event happens during that microsecond of gap.

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    Quote Originally Posted by slimshady View Post
    All they were doing was silver soldering a piece of music wire to the bottom of the bolt breechface. Laid flat vertically it essentially becomes a firing pin, crushing the rim as the bolt closes. On the bottom, the wire pushes the cartridge out of the mag and into the chamber so no issues with the rising rim hitting an extended firing pin during feeding. However, the stock hammer fire setup was retained. When he loaded the first round he rode the bolt home, letting it close gently enough it did not set off the first round with the wire. After he pulled the trigger, firing the first round with the OEM setup hammer hits firing pin method, the bolt would cycle and now hitting the round full force when the bolt closes the wire essentially converting it to an open bolt fixed firing pin system. With no means of stopping it except running out of ammo or jamming. He apparently had one of the good AR7 and mag combos that was reliable feeding. That appears to have been what they did with all the .22s they converted, first shot by the oem method, then empty the mag as the bolt cycled full force.

    Bolt bounce is not an issue normally with an open bolt fixed firing pin system as if it does bounce back it is after the round has already fired. With a hammer or striker system that drops the hammer or firing pin as the bolt closes can have problems with bolt bounce as it may close and then the firing pin is too far away from the cartridge as the bolt is bouncing back and the firing event happens during that microsecond of gap.
    That makes sense. Thanks.

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    The AR surprised me. If I understood correctly, the hammer was simply following the bolt home.

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    Correct. It alters the timing of the engagement between the face of the hammer and the firing pin as the hammer rides the bolt/carrier into battery. By removing the disconnector the hammer is captured only by the sear.

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    My lord, all the scraping around of the Colt SP1 on the concrete floor….

    But yes, interesting stuff!

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    The real irony is since RPB was forced to discontinue their open bolt semis and go to closed bolt, their redesign didn't really do all that much to prevent easy conversion. There is no bolt denial feature in the upper or lower, a FA spec open bolt drops right in and functions perfectly, you just can't stop it once the cocking handle is released. Freely available as an unregulated part. RPB and others have sold them like that for 30 years now without ATF complaining, with the open bolt semi you at least had to modify the parts to get it to go FA.

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    Thats the late and great Max Atchisson in the video.

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    Max Atchisson invented the drop-in auto sear DIAS and the lightning Link for the AR-15, the AA12 full auto shotgun the first known 9mm M16 among, the .22 conversion kits for the AR and M16, a .22 conversion for the UZI, and many other firearm inventions. He worked for MAC, RPB and SWD.

    Article; http://archive.smallarmsreview.com/d...idarticles=409

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    Quote Originally Posted by ferndog1 View Post
    Max Atchisson invented the drop-in auto sear DIAS and the lightning Link for the AR-15, the AA12 full auto shotgun the first known 9mm M16 among, the .22 conversion kits for the AR and M16, a .22 conversion for the UZI, and many other firearm inventions. He worked for MAC, RPB and SWD.

    Article; http://archive.smallarmsreview.com/d...idarticles=409
    With all due respect, the article makes no mention of Mr. Atchisson with respect to the drop in auto sear (DIAS) for converting the AR-15 pattern rifle to shoot full auto. It is my understanding that the DIAS was invented and sold by George Dodson, who, last I remember reading, was still imprisoned at a federal corrections facility due to his continued sale of unregistered DIASs.

    MHO, YMMV, etc.

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